1. Field of the Invention
The present invention relates generally to a method and apparatus for receiving data in a communication system, and more particularly, to a method and apparatus for receiving data after interference signals are cancelled by a terminal using multiple antennas in a wireless mobile communication system.
2. Description of the Related Art
In cellular mobile communication systems such as Code Division Multiple Access (CDMA), Wideband CDMA (WCDMA), and High Speed Downlink Packet Access (HSDPA) systems, a terminal receives data using multiple antennas. When the terminal is located at a boundary between a serving base station and an adjacent base station, a dual signal phenomena may occur, which is described in greater detail below.
FIG. 1 illustrates signal reception according to terminal positions in a cellular communication system.
As illustrated in FIG. 1, terminals 109 and 113 located in the cell boundaries receive not only the signals of their respective serving base stations 101 and 105, but also the signals of adjacent base stations 103 and 107, at similar strength. However, the signals of the adjacent base stations 103 and 107 serve as interference signals, causing a reduction in reception performance of the terminals 109 and 113. Therefore, in order to increase the reception performance of the terminals 109 and 113 in the cell boundaries, there is a need for techniques for canceling interference signals from adjacent base stations, as well as a receiver capable of canceling the interference signals.
Several methods such as the Minimum Mean Square Error (MMSE) scheme are used to cancel the interference signals. The terminals 109 and 113, located in the vicinity of their serving base stations, and thus having low power interference signals, use a reception method based on a Maximum Ratio Combining (MRC) scheme so as to perform accurate channel estimation thereon. Unfortunately, the MMSE scheme is greatly affected by noise, and the MRC scheme, though it guarantees a high reception performance, suffers from a reduction in the reception performance when the channel varies quickly.
The current mobile communication system, in which terminals each use multiple antennas, applies only a single reception method to the multiple antennas. Therefore, the mobile communication system does not take into consideration the amount of interference signals, making it difficult to guarantee optimal reception performance according to the positions of the terminals. In addition, optimal reception performance cannot be ensured using only the MMSE reception method, and the amount of interference received from other base stations should also be taken into consideration.